Center of Biological Research, Xuzhou Medical College, Xuzhou 221002, Jiangsu, China.
Life Sci. 2011 May 9;88(19-20):853-63. doi: 10.1016/j.lfs.2011.03.002. Epub 2011 Apr 6.
The standardized extract from the leaves of Ginkgo biloba (EGb761) is applied as a phyto-pharmacon in therapy of diverse cardiovascular disorders. However, the effects of EGb761 on bone-marrow mesenchymal stem cells (BMSCs) transplanted into the ischemic myocardium currently remain uncertain. In this study, the dosage-effects of EGb761 on BMSC survival in vitro and in vivo were investigated.
The ischemic microenvironment of rat BMSCs was simulated by hypoxia/serum deprivation (SD) and the rat myocardial infarction model was established. The rat BMSCs were cultured under hypoxia/SD or transplanted into the animal ischemic heart. The BMSC apoptosis was determined by FACS and TUNEL assay. Each apoptotic signal molecule's activity was assayed by immunoblot.
EGb761 showed a biphasic effect on the hypoxia/SD-induced BMSC apoptosis. Low concentration of EGb761 (10-100μg/ml) aggravated hypoxia/SD-induced apoptosis via Akt inactivation and an enhancement of caspase-9 and caspase-3 expressions, whereas high concentration of EGb761 (500-2000μg/ml) significantly prevented hypoxia/SD-induced BMSC apoptosis via the activated Akt and the inactivated caspase-9 and caspase-3. The animal study also indicated that the apoptotic index (AI) in the high concentration of EGb761 group was significantly lower than the low concentration of EGb761 group.
The biphasic effect of EGb761 is closely related to the PI3K-Akt and caspase-9 signaling pathways. The therapeutic concentration of EGb761 may be one of the vital factors determining the specific action of EGb761 on cell apoptosis. It is of significant clinical implication to investigate the mechanisms of the biphasic effect of EGb761.
银杏叶提取物（EGb761）的标准化提取物作为植物药应用于多种心血管疾病的治疗。然而，EGb761 对骨髓间充质干细胞（BMSCs）移植到缺血心肌中的作用目前尚不确定。本研究旨在探讨 EGb761 对 BMSC 体外和体内存活的剂量效应。
通过缺氧/血清剥夺（SD）模拟大鼠 BMSC 的缺血微环境，并建立大鼠心肌梗死模型。将大鼠 BMSC 在缺氧/SD 条件下培养或移植到动物缺血心脏。通过 FACS 和 TUNEL 检测法测定 BMSC 凋亡。通过免疫印迹法测定每个凋亡信号分子的活性。
EGb761 对缺氧/SD 诱导的 BMSC 凋亡呈双相作用。低浓度 EGb761（10-100μg/ml）通过 Akt 失活和增强 caspase-9 和 caspase-3 的表达加重缺氧/SD 诱导的凋亡，而高浓度 EGb761（500-2000μg/ml）则通过激活 Akt 和失活 caspase-9 和 caspase-3 显著预防缺氧/SD 诱导的 BMSC 凋亡。动物研究还表明，高浓度 EGb761 组的凋亡指数（AI）明显低于低浓度 EGb761 组。
EGb761 的双相作用与 PI3K-Akt 和 caspase-9 信号通路密切相关。EGb761 的治疗浓度可能是决定 EGb761 对细胞凋亡特定作用的重要因素之一。研究 EGb761 双相作用的机制具有重要的临床意义。
